A wide variety of dispensers for insecticide vapors, air freshener vapors, and other air-treating vapors are known in the art. More specifically, it is known to provide a dispenser in which volatilizable materials, such as certain insecticides and air fresheners, may be driven by heating from substrates in which they are contained. The substrates containing such volatilizable materials are typically small mats of cellulosic material such as paperboard. Heat is applied to such mats through an electrically heated plate against which such mats are held. A heating coil is used to heat the plate. The mats are replacable.
The rate of vapor-dispensing in devices of the type described can vary unacceptably if the degree of contact between the mats and the heating plate varies. For example, if for a first mat there is a firm face-to-face contact with the heating plate and for a second mat the contact is relatively loose, volatilization will occur more rapidly in the first mat than in the second due to greater heat transfer.
Some devices of the prior art do not provide adequate means for causing an appropriate firm contact of such mats with the heating plate. In some cases, such devices may be designed to provide the appropriate degree of mat-plate contact only for mats of a given thickness, while thinner mats would be held in place too loosely and thicker mats might not even be properly insertable into the device. Thus, there has been a need for an improved device for holding the impregnated mats against the heating plate.
A related disadvantage in certain prior art devices is the difficulty associated with insertion and/or release of replaceable impregnated mats. Such difficulties relate not only to the thickness of such mats as described above but to the method of mat replacement. Some prior art devices require that a used mat be displaced by insertion of new mat. Such loading and unloading steps may be difficult to carry out and/or difficult for consumers to understand. There has been a need for an improved mechanism for facilitating insertion and/or release of replaceable impregnated mats.